Pr. Moog et al., RESPONSES TO IRON-DEFICIENCY IN ARABIDOPSIS-THALIANA - THE TURBO IRONREDUCTASE DOES NOT DEPEND ON THE FORMATION OF ROOT HAIRS AND TRANSFERCELLS, Planta, 195(4), 1995, pp. 505-513
Arabidopsis thaliana (L.) Heynh. Columbia wild type and a root hair-le
ss mutant RM57 were grown on iron-containing and iron-deficient nutrie
nt solutions. In both genotypes, ferric chelate reductase (FCR) of int
act roots was induced upon iron deficiency and followed a Michaelis-Me
nten kinetic with a K-m of 45 and 54 mu M Fe-III-EDTA and a V-max of 4
2 and 33 nmol Fe2+.(g FW)(-1).min(-1) for the wild type and the mutant
, respectively. The pH optimum for the reaction was around pH 5.5. The
approximately four fold stimulation of FCR activity was independent o
f formation of root hairs and/or transfer cells induced by iron defici
ency. Iron-deficiency-induced chlorosis and the development of a rigid
root habit disappeared when ferric chelate was applied to the leaves,
while FCR activity remained unchanged. The time course of the respons
es to iron deficiency showed that morphological and physiological resp
onses were controlled separately.